HDDC Brief Overview - Research Focus The Harvard Digestive Disease Center is focused on the cell biology and function of epithelial cells of the alimentary tract, liver, and pancreas, and the complex interactions of epithelia with the microbial flora and subepithelial cells of the lamina propria that manifests itself in mucosal immunity and allergy, innate host defense, digestion and absorption, the development of gastrointestinal neoplasia, and the many other functions of the Gl tract. The biology of epithelial cells and their interactions with subepithelial tissues dictates organ function in the Gl tract and explains how the host relies upon and yet defends against components of the natural environment including food and non-nutrient antigens, the commensal and pathogenic microbial flora, toxins, and microbial products. Development and maintenance of this complex system requires rapidly adaptive mechanisms for cross-talk among the epithelial cells lining the mucosa surface, immunocompetent and supporting cell types in the sub-epithelial space, and the environment. The title of our Center, Integrated Epithelial and Mucosal Biology reflects this research focus. This emphasis on the epithelial cell and its mucosal environment reflects the historical and contemporary strengths of the Harvard Digestive Disease Center and provides a unifying focus for scientists with interests in the diverse functions of the gastrointestinal tract. The Center aims to facilitate multidisciplinary research in this field by providing technical resources, core services, scientific expertise, and an important meeting point to foster close scientific and intellectual relationships among independent investigators in Harvard-affiliated hospitals, the Harvard Medical School and adjacent research institutions in Boston's Longwood Medical Area. We also aim to recruit new and established investigators to the field. Our overarching mission is to foster and expand basic and translational science in fields related to digestive diseases by: connecting people, 'creating opportunity, and ^extending resources.